Compensator



R. A. LEE

COMPENSATOR April 22, 1952 2 SHEETS-SHEET 1 Filed July 14, 1949INVENTOR. R/CH/QD A. LEE

April 22, 1952 R, A, LEE 2,593,9(12

coMPENsAToR Filed July 14, 1949 2 SHEETS- SHEET 2 FIG. 2

INVENTOR. ,4P/CHAR@ A. EE BY @754 zza-e Patented Apr. 22, 1952COMPENSATOR Richard A. Lee, West Englewood, N. J., assignor to BendixAviation Corporation, Teterboro, N. d., a corporation of DelawareApplication July 14, 1949, Serial No. 104,630

12 Claims.

The present invention relates to repeaters and more particularly to arepeating and indicating system for remote indicating compasses.

At the present time, Compasses are generally of two types, the magneticneedle type and the earth inductor type which utilizes some elementother than a magnetic needle, usually a closed coil spinning in theearths field for generating voltages that are made to actuate anindicating mechanism to indicate a course or bearing in azimuth. SuchCompasses are well known, but have heretofore had many limitations whichrestrict their usefulness as a navigation instrument.

One of the principal difficulties of such compasses has been to repeatthe compass position at a remote repeater indicating instrument, and tocompensate such repeating instrument for known errors in the compassitself as shown in a calibration chart thereof, for variation errorsintroduced by the environment in which the in strument is placed, anddeviation errors caused by the discrepancy between the location of themagnetic and geographic poles, respectively.

In the past, corrections have been made by making the needle of therepeater instrument dependent upon the configuration of a iiexible camtrack which may be adjusted at a plurality of points thereon byindividual set screws. In order to get to the set screws,` a removablecover had to be provided so that the set screws could be adjusted by ascrewdriver or a wrench. Aside from being cumbersome, such anarrangement had the distinct disadvantage that unless the operator wasthoroughly familiar with the instrument and thus, able to select thecorrect set screw, the instrument was often put out of commission bymisadjustment. This is particularly serious when the accuracy of acomputer is dependent upon the correctness of the repeating instrument,which very often is the case.

The present invention contemplates the provision of a novel deviceinterposed between a master instrument, such as a magnetic compass, anda repeater instrument, whereby the repeater instrument may easily becorrected for all the above errors.

One of the objects of the 'present invention, therefore, is to provide anovel, simple and improved adjusting mechanism for a repeaterinstrument.

Another object is to provide a novel adjusting mechanism for a repeaterinstrument, whereby corrections may be made at a preselected nurn`|- berof positions of the indicator thereof by a single, conveniently locatedoperating member.

Another object is to provide a novel adjusting mechanism for a repeaterindicator, whereby corrections for deviation and variations may be maderelative to the position of a master indi cator at a plurality of spacedpositions of the indicator needle of the repeater indicator.

Another object of the invention is to provide a novel compass repeatingsystem whereby corrections for inherent errors in a master compass,deviation errors and variation errors may be introduced so that thereading on a iinal repeater indicator need not be referred to acalibration chart, but may be read directly from the azimuth scalethereof.

Still another object is to provide novel means whereby a flexible cammay be adjusted at a plurality of points by single adjusting means.

A further object of the invention is to provide novel means whereby thecontour of a cam track on which the relative position of a pair ofrotatable interconnected members is dependent may be changed at aplurality of points therealong by single adjusting means.

A still further object is to provide single novel adjusting means formaking a repeater indicator accurately track a master compass through360, and to compensate for errors in the master compass and thetransmission channel.

The foregoing and other objects and advan; tages of the invention willappear more fully hereinafter from a consideration of the detaileddescription which follows, taken together with the accompanying drawingswherein one embodiment of the invention is illustrated by wasT ofexample. It is to be expressly understood, however, that the drawingsare for purposes of illustration and description only, and are notintended as a definition of the limits of the invention.

In'the drawings, wherein like reference characters refer to like parts:

Figure 1 is a schematic wiring diagram of a system embodying theinvention; and

Figure 2 is a perspective View of the novel adjusting means per se.

For a better understanding of the invention, reference is had to Figurel, wherein a conventional repeater system is shown comprising a compassgenerally indicated at l0, which may be any type of compass orinstrument capable of imparting rotation to an output member such as ashaft l2 to position an indicator M and rotor l5 of inductive device i8.The rotor is excited from a source cf A. C. power, and movement of therotor will induce a voltage in stator 20 of a phase depending on thedirection of the displacement, which voltage will be repeated in stator22 of inductive device 24 and will induce a voltage in rotor 26corresponding to the voltage in rotor I6. Rotor 26 is connected to amotor 28 through an amplifier and discriminator 30, which may be ofconventional design, and hence, not illustrated and described in detail.

The motor 23 is arranged to rotate the rotor back to null position whena voltage is induced therein in the usual manner. An indicator 32 isconnected to and positioned with rotor 26 through adjusting means 26,which will presently be described, to indicate the position of compass land repeat the position lof indicator I4. Indicator 34 s connected toand positioned with stator 22 by a manually operable knob 36.

In the system so far described, the pointer of indicator i4 will showthe position of compass I0 on an azimuth scale. The magnetic element ofthe compass, however, will not point to true north even if influencedsolely by the earths magnetism, and this error, commonly termedvariation, may be corrected forby manually operating knob 36 to rotatestator 22 an amount corresponding to the variation at the particularlocation of the craft on which the compass is mounted. The amount ofcorrections inserted is shown by indicator or variation pointer 34.

When compass i6 is situated in an environment that distorts the earthsmagnetic field, errors due to deviation from the earths field will,unless corrected, cause the pointer of indicators I4 and 32 to give anerroneous magnetic bearing. According to the present invention, a novelcam correcting or compensating mechanism, generallr indicated at 26, isinserted in the link connecting rotor 26 cf inductive device 2li withindicator 32.

One embodiment of the novel compensating mechanism is shown inperspective view in Figure 2, wherein wiring has been omitted for thesake of clarity. Motor 28 is shown as being connectedto rotor shaft 4|]oi inductive device 24 through reduction gearing generally indicated at42, interconnected gears 44 and 46 and pinion 48. Pinion 46, which ismounted on rotor shaft 4|), is connected to heading pointer 32 throughgears 44 and 46 and shaft 52 secured to gear 44. Variation pointer 34 ismounted on sleeve 54 surrounding shaft 52 which sleeve is rigidlyconnected to gear 56. Spaced from gear 56 and movable therewith througha plurality of annularly spaced screw threaded shanks 60 is an annularilegible ring or cam Vtrack 62. In the illustrated embodiment there are12 shanks spaced at intervals of 30. The shanks are in threadedengagement with gear 56 and rotatably fastened to cam track 62 in such amanner as to be axially stationary therewith. Splined to the Shanks, ormade integrally1 therewith, are gears, three of which are identified as64, 65 and 66, arranged to be selectively engageable with pinion 68.Pinion 68 is rotatable with manually operable knob 31 and connectedthereto by a shaft 10. Shaftf16 is axially movable and has an eX- andedsection 12 connected thereto by a ramp A detent 16 having a sharp heelportion 11 is spring biased against shaft 16. By manually pulling knob31 outwardly or to the right, as viewed in the drawing, stop 16 willslide up ramp 14 to permit engagement of pinion 68 with a preselectedone of gears 6ft, 65, 66, etc., lwhereby the distance between gear 56and iiexible cam track 62 at this particular point may be varied byturning knob 31. By successively engaging pinion 68 with all the gears64, 65, 66, etc., cam track 62 may be given any desired axialdeformation, within certain limits, with respect to a planeperpendicular to the a-Xis of rotation of shaft 52 or sleeve 1Brotatably mounted thereon. A cam fol.- lower, such as a roller member16, is carried by a forked member 86 pivoted to sleeve le as by pins 82.

Cam track 62 may be of spring steel and its surface will readily conformto adjustment resulting in a smooth track for roller lil. Rigidlyconnected to member 86 is a rod 64 extending through a slot or opening86 in gear 46 but out of engagement therewith through a hole it in gear44. A spring 96 is attached to pin 62 er;- tending from gear 46 and topin 65. extending from gear 44, as shown, and biases gear 44 in aclockwise direction, as seen from the right in the drawing, with respectto gear 46. This will force the edge of hole 8S against rod 24, which inturn Will bias roller 19 against'cam track 62 through the bell crankformed by rod Sil and forked meniber 80.

Thus, it will be seen that, as roller '16 is rotated relative to camtrack 62, axial distortions of the cam track will cause relativerotational movement between gear 46, which is rotatably xed with respectto the roller 19 and forked member 86, and gear 44 which is held fast bymotor 28 and reduction gearing 42. Sleeve 18 surrounds shaft 52 and isfree to rotate relative thereto.

The casing 96 of the inductive device and hence stator 22 is rotatableby manually operable knob 36 acting on gear |04 through a shaft E66 andpinion |02 secured thereto. Gear |62 may be made integrally with casing66 or suitably mounted thereon. Also mounted on shaft |66 is a gear |06meshing with intermediate free gear |08 which in turn is in mesh withgear 56.

Also mounted on shaft |60 and keyed thereto in alignment with detent 16is a notched disc ||0. The notches are so spaced that when one of gears64, 65, 66 is in meshing position with gear 68, the heel 11 of detent 16will be in front of one of the notches. When knob 36 and shaft 10 arepulled outwardly or to the right as viewed in the drawing, detent 16will ride up ramp 14 onto expanded section 12 of the shaft and thusforce the heel 11 of the detent into the notch so as to prevent rotationof knob 36 when pinion 68 is in adjustable position. Detent 16 Willalso, of course, prevent the withdrawal of shaft 16 except when one ofthe gears 64, 65 and 66 is in meshing position with gear 68.

In order to limit the total rotation of the casing 96 to 180 each wayfrom zero position, a stop mechanism, generally indicated at H2, isprovided. This stop mechanism may be of any convenientdesign and isshown in the drawing as including a threaded portion ||4 of shaft |66. Asplit nut ||6 is in engagement with the threaded portion and isprevented from rotating therewith as by a stationary member H6 riding ina groove |26 in the split nut. The travel of the split nut in eitherdirection is limited by stops |22 and |23.

Coming now to the operation of the above-described device, let us assumethat the craft is headed or pointed in such a direction that the pointerI4, Fig. 1, indicates a bearing of 270, and that all the parts are inthe position illustrated in Fig. 2. If, from an appropriate standard, itappears that the indicated bearing should be, for instance, 260,adjustment is made by turm'ng knob 31, whereby the meshing gear 64 willcause the point at which the gear shank is attached to the gear track 62to be moved away from or toward gear 56 as the case may be. This motionwill be transmitted to gear 46 through a bell crank fulcrumed about pins82 in sleeve 18 and comprising cam follower 19, forked member 80 and rod84. The pivotal movement of forked member 80 about pins 82 effectsrotation of sleeve 18 and gear 45 relative to shaft 52 to drive pinion48, thereby displacing rotor 26 to provide a signal which drives motor28, the latter in turn driving gear 44 through reduction gearing 42.Shaft 52 and pointer 32 move with gear 44 in a direction depending uponthe sense in which knob 31 is rotated. In considering the abovesequential movement of elements, it is to be noted that when roller 13is moved away from or toward cam track 62 gear 44 is held iixed by motor28, and rod 84 is restrained from moving angularly about pins 82 becauseof the engagement of the rod with the edge of opening 88. Since camroller 19 is biased against cam track 62 by the spring connection 90, 92and 94, and is moved away from or toward the cam by the contour thereof,a turning or twisting motion of foked member 80, sleeve 18 and gear 46relative to shaft 52 and gear 44 will be eilected. The knob 31 isrotated until pointer 32 indicates true heading of 260. Gear 68 is nowdisengaged from gear 64 by pushing knob 31 in or to the left, as Viewedin the drawing, whereby stop 16 will return to normal position bysliding oi expanded section 12 of shaft 10 and release notched disc H0,thus freeing shaft |00.

In order to bring gear 65 into engaging position with gear 68, knob 36is turned manually until gear 65, which follows gear 64 is in properposition as indicated by suitable visual means on the dial (not shown)which may be dependent on the position of pointer 34. Now cam follower12 has to be brought into axial alignment with the shank of gear 65,because as the heading of the ship was changed, the position of theheading pointer and hence, the position of the unit comprising gears 44and 46, rod 84, forked member 80 and cam follower 19 was displaced acorresponding amount relative to gear 66 and cam track E2.

In order to bring roller 19 into axial alignment with the shank of gear65, the casing S and hence stator 22 of inductive device 24, is,according to this invention, rotated simultaneously with rotation ofgear 56 by pinion |02- mounted on shaft |00 and meshing with casing gear|04. rIhis will cause relative movement between stator 22 and rotor 26and a signal will be developed in the latter. This signal will causemotor 28 to rotate in such a direction as to bring the rotor` back to anull position and will simultaneously bring roller 19 into properposition with respect to gear 65 and its shank when the latter gear isin meshing position with gear 68. This is brought about by properlyselecting the gear ratios between pinion H02 and gear |04, and sincegears 44 and 46 are resiliently coupled together by spring 90, thespring will cause gear 46 to follow gear 44 when the latter is rotatedby motor 28 thereby effecting movement of roller 19 to track gear 56. Itwill be seen that the gear ratios between gears |06 and 56 and betweenpinion |02 and gear M4 are selected so that the roller 19 eiectivelytracks gear 56 when knob 36 is operated. i

In the present illustration, gears 64, 65, 66, etc., are 30 apart, andto correct the complete azimuth scale, the craft will have to be turnedat 30 intervals. Thus, as the heading of the plane is changed toindicate 300, roller 19 will be positioned in alignment with gear 65.When knob 36 is now turned until the gear 65 is in meshing position withgear 68, roller 19 will also be in proper position by the action ofmotorA 28 as explained above. In this position, notched disc H0 willhave a notch in position to receive the heel 11 of detent 16, and byVpulling knob 31 to the right, gear 63 is meshed with gear 65. Knob 68 isnow adjusted until the necessary correction is set in by axiallydisplacing iexible cam 62 at this, particular point whereby the camfollower will cause relative motion between gears` 44 and 46 aspreviously explained, and the amount of correction set in may bedetermined by observing the displacement of pointer 32. Gears 68 and 65are now disengaged and the heading of the craft is changed another 30 atwhich time roller 19 is aligned with gear 66. Knob 3d is again turneduntil this gear is in meshing position with gear 68, at which time theyare brought into mesh and pointer 32 is corrected for this position andso on until the complete azimuth scale of indicator I4 has been covered.

It will be apparent to those skilled in the art that this compensatingmechanism may also be used to calibrate a repeater instrument in orderto make it track a standard instrument precisely. By introducing asignal into the signal circuit of the standard, the standard may becaused to be displaced a preselected amount and the repeater may then beadjusted in accordance therewith by the above-described device, and, ifnecessary, correct it for known errors in the standard;

After the repeater instrument is properly calibrated, the magneticvariation may be inserted `by movement of knob 36 until pointer 34indicates the variation desired. This makes it convenient for thenavigator to change the variation during night.

Although only one embodiment of the invention has been illustrated anddescribed in detail, it is to be expressly understood that the inventionis not limited thereto. Various changes can be made in the design andarrangement of the parts without departing from the spirit and scope lofthe invention as the same will new be understood by those skilled in theart.

What is claimed is:

l. In a compensating mechanism for a` repeater indicator to compensatefor predetermined errors in a master compass in which rotor and statorelements of van inductive device are rela.- tively displaceable inresponse to movements in said master compass, a member connected to saidrotor element and movable therewith, a repeater indicator, a memberconnected to said indicator and movable therewith, a flexible annularcam track, a plurality of adjustable means connected to said cam trackand spaced therealong to change the contour thereof, a cam followeradapted to follow the contour of said cam track associated with one ofsaid members and comprising a bell crank pivotally mounted on said onemember and adapted to engage the other member, resilient meansconnecting said members and providing a driving connection between saidmembers and permitting relative displacement therebetween proportionalto variationsin the contour of said flexible cam track, manuallyoperated actuating means arranged for engageinto engagement with said-actuating means and simultaneously rotating the stator element of saidinductive device to bring said cam follower into responsive positionrelative to said preselected adjustable means.

2. Means for compensating a compass for deviation errors comprising anangularly displaceable cage carrying a deformable cam track thereon, aplurality of spaced adjustable members supported by the cage andengaging the cam track whereby adjustment of said members provides axialdeformation of the track, a pivotally mounted cam follower engaging thecam track and pivoted in accordance with the deformations on the track,a manually operable member for selectively operating said adjustablemembers, and a second manually operable member engaging said cage fordisplacing the latter to bring a preselected one of said adjustablemembers in engagement with said first manually operable member.

3. Means for compensating a compass for deviation errors comprising anangularly displaceable member carrying a deformable cam track thereon, aplurality of spaced adjustable members supported by the member andengaging the cam track whereby adjustment of said members provides axialdeformation of the track, an angularly displaceable and pivotallymountedcam follower riding on the cam track and pivoted in accordancewith the deformations on the cam track, a manually operable member forSelectively operating said adjustable members, a secn ond manuallyoperable member engaging said displaceable member for displacing thelatter to bring a preselected one of said adjustable members inengagement with said firstl manually operable member, and means operatedby said second manually operable member for displacing said cam followerto a position in alignment with said preselected adjustable member.

4. Means for compensating a compass for deviation errors comprising anangularly displaceable member carrying a deformable cam track thereon aplurality of spaced adjustable members supported by the member andengaging the cam track whereby adjustment of said members provides axialdeformation of the track, an angularly displaceable and pivotallymounted cam follower riding on the cam track and pivoted in accordancewith the deformations on the cam track, a manually operable member forselec tively operating said adjustable members, a second manuallyoperable member engaging said displaceable member for displacing thelatter to bring a preselected one of said adjustable members inengagement with said first manually operable member, a signal developingdevice operated by said second manually operable member for developing acontrol signal, and a motor operated by said signal for displacing saidcam follower to a position in alignment with said preselected adjustablemember.

5. The combination in a craft compass system having a displaceabledevice for eveloping a signal corresponding to a predetermined headingchange, a pointer, and a motor energized by the signal for returning thedevice to a no-signal position and displacing the pointer to indicatethe new craftheading, of means for compensating pointer movement fordeviation error comprising an axially deformed cam track, a pivotallymounted cam follower engaging said track and connected to the motor formovement along said track, said folllower being pivoted in accordancewith the deformation of said track, and a connection between saidfollower and the signal device for displacing the latter an amount iproportional to the pivotal movement of the cam follower whereby asignal is developed by the device to operate said motor to therebydisplace said pointer an additional amount.

6. In a repeater system of the type including a master indicator, arepeater indicator, and induction means responsive to movements of saidmaster indicator for actuating said repeater indicator, a compensatingdevice interposed between said master indicator and said repeaterindicator for compensating forv errors in said master indicator andcomprising a member rotatable by said induction means, a cam followercarried by said member, a member connected to said repeater indicator, acam track, means for biasing said cam follower against said cam track,means connecting said members for transmitting to one of said membersthe angular movement of the other of said members altered by an amountproportional to the movement of the cam follower produced by the cam'action of the cam track, a plurality of adjustable means spaced alongsaid cam track for changing the contour thereof, actuating means forsaid contour changing means, and means connected to said cam track fordriving said cam track to selectively bring each one of said cam trackcontour-changing means into engagement with said .actuating means andfor simultaneously bringing said cam follower into alignment with thepreselected cam track contour-changing means.

'7. A compensating device comprising a first rotatable member, a camfollower carried by and rotatable with said member, a cam track engagedby said follower so that the latter follows the contour of ,said camtrack, a second rotatable member, means connecting said members fortransmitting to one of said members the angular movement of the other ofsaid members altered by an amount proportional to the movement of thecam follower produced by the cam action of the cam track, a plurality ofadjustable means spaced along said cam track for changing the contourthereof, manually operable actuating means mounted in juxtaposition withsaid contour-changing means, said actuating means bcing adapted uponmanual operation thereof to be brought into a position to engage one ofsaid contour-changing means, and means for selectively bringing each oneof said contourchanging means into engagement with said actuating means.

8. A compensating device comprising a first rotatable member, a camfollower carried by and rotatable with said member, a cam track engagedby said follower so that the latter follows the contour of said camtrack, a second rotatable member, means connecting said members fortransmitting to one of said members the angular movement of the other ofsaid members altered by an amount proportional to the movement of thecam follower produced by the cam action of the cam track, a plurality ofadjustable means spaced along said cam track for changing the contourthereof, actuating means for said contour-changing means, and meansconnected to said cam track for driving said `cam track to selectivelybring each one of said contour-change ing means into engagement withsaid actuating means and for simultaneously bringing said cam followerinto alignment with the preselected cam track contour-changing means.

9. A compensating device comprising a flexible annular cam track, meansfor adjusting the c`ontour of said cam track at a plurality of spacedpoints therealong, a roller member biased against said cam track andpivotally mounted on a sleeve member so as to engage said cam track andfollow the contour thereof, a disc rigidly mounted on said sleeve, ashaft, a disc mounted on said shaft adjacent said first-mentioned disc,means connecting said discs for transmitting to one of said discs theangular movement of the other of said discs altered by an amountproportional to the movement of the roller member produced by the camaction of the cam track, actuating means for said contour adjustingmeans, and means for selectively bringing each one of said contouradjusting means into engagement with said actuating means.

10. A compensating device for compensating for compass errors in amaster compass, comprising an annular deformable cam track, a camfollower for cooperation with said cam track, a member movable with anindicator, a member movable with said master compass, means connectingsaid members for transmitting to one of said members the angularmovement of the other of said members altered by an amount proportionalto the movement of the cam follower produced by the cam action of thecam track, adjustable means for said cam track spaced therealong tochange the contour thereof, manually operable actuating means mounted injuxtaposition with said adjustable means, said actuating means beingadapted upon manual depression thereof to be brought into a position toengage one of said adjustable means, and means for bringing apreselected one of said adjustable means into engagement with saidactuating means.

11. A compensating device for compensating for compass errors in amaster compass, comprising an annular deformable cam track, a camfollower for cooperation with said cam track, a member movable with anindicator, a member movable with said master compass, means connectingsaid members for transmitting to one of said members the angularmovement of the other of said members altered by an amount pro- CIIportional to the movement of the cam follower produced by the cam actionof the cam track, adjustable means for said cam track spaced therealongto change the contour thereof, manually operable actuating means mountedin juxtaposition with said adjustable means, said actuating means beingadapted upon manual operation thereof to be brought into a position toengage one of said adjustable means, and means ccnnected to said camtrack for driving said cam track to bring a preselected one of saidadjustable means into engagement with said actuating means and forsimultaneously bringing said cam follower into alignment with thepreselected cam track contour-changing means.

12, Compensating means comprising a driving member and a driven member,a flexible cam track, a plurality of compensating means cooperating withsaid cam track to change the contour of said cam track and spacedtherealong, a cam follower displaceable according to variations in thecontour of said cam track and means connecting said members fortransmitting to one of said members the angular movement of the other ofsaid members altered by an amount proportional to the movement of thecam follower produced by the cam action oi the cam track, manuallyoperable actuating means mounted in juxtaposition with any one of saidcompensating means, said actuating means being adapted upon manualoperation thereof to be brought into a position to engage one of saidcompensating means, and a manually operable means connected to said camtrack for driving said cam track to bring a preselected one cf saidcompensating means into engaging position with said actuating means andsimultaneously causing said cam follower to be brought into position toindicate the change of contour imparted to said cam track by movementsof said compensating means by said actuating means.

RICHARD A, LEE.

REFERENCES CITED rlhe following references are of record in the iile ofthis patent:

UNITED STATES PATENTS Number Name Date 1,779,145 Proctor Oct. 21, 19301,807,919 Kolster June 2, 1931 2,308,566 Noxon Jan. 19, 1943

